installing usa maps on mio map c320 [Mio]

I'm trying to install USA maps on my mio, every time I copy the USA maps to the maps directory and turn on my device, I see a key symbol near the usa maps and I can choose it.I bought the gps device in Israel with israel's maps.How can I activate the usa maps?I have a another sd card the I copy on it the softeware and the map and I donwnloaded few crack to the mio map softwares, but it doesn't work.does anybody know when I can get USA maps that work?thanks